Pathogenecity of Beauveria bassiana and Metarhizium anisopliae, to the Two Spotted Spider Mites, Tetranychus urticae, (Acari: Tetranychidae) at Different Temperatures and in Greenhouse Condition

Abstract

Pathogenecity of entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae isolates of Ethiopian origin on eggs and adults of the two spotted spider mites, Tetranychus urticae, effect of temperature on virulence, as well as potentials of isolates in the greenhouse condition was assessed during October 2008 to May 2009 at Plant protection Research center in Ambo. All the isolates tested (B. bassiana 9614 and 9609, and M. anisopliae MM and PPRC 6) caused high mortality to the eggs of the two spotted spider mites compared to the control groups. Significant differences of pathogenicity were observed among isolates kept at different temperature regimes. Temperature regimes of 25°C and 30°C were suitable for the isolates M. anisopliae MM and B. bassiana 9614 compared to 20°C and 35°C. All the four fungal isolates used caused significantly higher mortality compared with the untreated control groups under the greenhouse condition and the highest mortality was 89.4%. As a consequence leaves treated with the fungal isolates had less damage that may be attributed to fewer number of surviving mites. The study showed that M. anisopliae and B. bassiana are able to kill the two spotted spider mites eggs and adults, and can be used as substitute or complement to synthetic chemicals most of which lack ovicidal activity.

Keywords: Entomopathogens; Isolates; Mortality; Temperature; Two Spotted Spider Mites.